Usually they simply just don't have enough information or get the wrong information from unreliable sources. They don't understand something, but that doesn't make it a scam.
Although there's a lot of ways for them to learn and have known about crypto, but people chooses not to. So, this thing will really depend on them if they want to know it then Google is the key, if they don't then they won't find a way to get through it.
Anyway, as for my family and friends that still don't believe in Bitcoin up to this date, time will come they will tell to me that why I didn't push them to believe in me.
Bitcoin is not actually scam. You are just saying that maybe because you invested in some project that is not trusted. There are lots of scammers in here since we are in the world of internet, there are lots of people you dont know. They are taking advantage of other people just to get their money. I actually read different reviews before joining or supporting a particular project just to make sure that my time is not wasted on nothing. I am reading articles on a particular project so that my time and money is worth it if I invested in that ICO. You can say that because the market is on downfall, you should wait for the right time that the market will recover since the nature of cryptocurrency is volatility, meaning the value is changing time by time when there is transaction happening.